Field of the Invention
The present invention relates to a thin film piezoelectric element substantially containing no lead therein. The present invention also relates to a piezoelectric actuator, a liquid ejection head, a liquid ejection apparatus, a shake correction mechanism, a variable shape optical element, a movable optical member, an optical device, an image pickup apparatus, an optical switch, a micromirror device, an ultrasonic wave probe, an ultrasonograph, a sound component, an angular velocity sensor, a vibration power generator, a surface acoustic wave generator, a piezoelectric shutter, and an electronic apparatus using the piezoelectric element.
Description of the Related Art
A thin film piezoelectric element typically includes a lower electrode, an upper electrode, and a piezoelectric film sandwiched therebetween. The piezoelectric film is formed of a polycrystal of a ferroelectric metal oxide. A typical principal component of the piezoelectric film is an ABO3 type perovskite metal oxide, e.g., lead zirconate titanate (hereinafter referred to as “PZT”). However, PZT contains lead as an A-site element, and thus, influence thereof on the environment is perceived as a problem. Therefore, a piezoelectric film containing no lead therein (lead-free piezoelectric film) is required.
As a lead-free piezoelectric film, a barium zirconate titanate film is known. In Japanese Patent Application Laid-Open No. 2011-243722, it is disclosed that, through adding of a manganese oxide of 2 mol % or more and 4 mol % or less to a sum of titanium and zirconium of barium zirconate titanate, a crack in the piezoelectric film is suppressed. However, the disclosed composition has a large dielectric loss, and thus, has a problem in power consumption and heat generation when a piezoelectric element is driven. There is also a problem in that a piezoelectric constant of the lead-free piezoelectric film is insufficient for practical use.
The present invention has been made to solve the problems described above, and provides a thin film piezoelectric element containing no lead therein, which has a high Curie temperature at a piezoelectric film portion thereof, a small dielectric loss, and a high piezoelectric constant at room temperature.
The present invention also provides a piezoelectric actuator, a liquid ejection head, a liquid ejection apparatus, a shake correction mechanism, a variable shape optical element, a movable optical member, an optical device, an image pickup apparatus, an optical switch, a micromirror device, an ultrasonic wave probe, an ultrasonograph, a sound component, an angular velocity sensor, a vibration power generator, a surface acoustic wave generator, a piezoelectric shutter, and an electronic apparatus using the piezoelectric element.